Credit Loss Reserves - Summarizes Changes in Credit Loss Reserves by Product/Class and Related Receivable Balance by Product (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period	$ 2,217		$ 3,273
Provision for credit losses	27	[1]	2
Charge-offs	(147)	[2]	(311)	[2]
Recoveries	13		33
Total net charge-offs	(134)		(278)
Credit loss reserves at end of period	2,110		2,997
Reserve components:
Collectively evaluated for impairment	207		539
Individually evaluated for impairment	1,875	[3]	2,405	[3]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	27		52
Receivables acquired with deteriorated credit quality	1		1
Total credit loss reserves	2,110		2,997
Receivables:
Collectively evaluated for impairment	11,387		13,774
Individually evaluated for impairment	9,802	[3]	10,767	[3]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	529		927
Receivables acquired with deteriorated credit quality	11		13
Total receivables	21,729		25,481
First Lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period	1,898		2,777
Provision for credit losses	37	[1]	(24)
Charge-offs	(108)	[2]	(248)	[2]
Recoveries	12		21
Total net charge-offs	(96)		(227)
Credit loss reserves at end of period	1,839		2,526
Reserve components:
Collectively evaluated for impairment	154		414
Individually evaluated for impairment	1,657	[3]	2,060	[3]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	27		51
Receivables acquired with deteriorated credit quality	1		1
Total credit loss reserves	1,839		2,526
Receivables:
Collectively evaluated for impairment	9,863		11,924
Individually evaluated for impairment	8,936	[3]	9,789	[3]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	500		876
Receivables acquired with deteriorated credit quality	9		10
Total receivables	19,308		22,599		20,153
Second Lien [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period	319		496
Provision for credit losses	(10)	[1]	30
Charge-offs	(39)	[2]	(63)	[2]
Recoveries	1		8
Total net charge-offs	(38)		(55)
Credit loss reserves at end of period	271		471
Reserve components:
Collectively evaluated for impairment	53		125
Individually evaluated for impairment	218	[3]	345	[3]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	0		1
Receivables acquired with deteriorated credit quality	0		0
Total credit loss reserves	271		471
Receivables:
Collectively evaluated for impairment	1,524		1,850
Individually evaluated for impairment	866	[3]	978	[3]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	29		51
Receivables acquired with deteriorated credit quality	2		3
Total receivables	2,421		2,882		2,517
Personal non-credit card [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Credit loss reserves at beginning of period	0		0
Provision for credit losses	0	[1]	(4)
Charge-offs	0	[2]	0	[2]
Recoveries	0		4
Total net charge-offs	0		4
Credit loss reserves at end of period	0		0
Reserve components:
Collectively evaluated for impairment	0		0
Individually evaluated for impairment	0	[3]	0	[3]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	0		0
Receivables acquired with deteriorated credit quality	0		0
Total credit loss reserves	0		0
Receivables:
Collectively evaluated for impairment	0		0
Individually evaluated for impairment	0	[3]	0	[3]
Receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell	0		0
Receivables acquired with deteriorated credit quality	0		0
Total receivables	$ 0		$ 0

[1] The provision for credit losses for real estate secured receivables during the first quarter of 2015 was impacted by a release of approximately $19 million associated with a correction to our credit loss reserve calculation for a segment of our portfolio.

[2] For collateral dependent receivables that are transferred to held for sale, existing credit loss reserves at the time of transfer are recognized as a charge-off. We transferred to held for sale certain real estate secured receivables during the three months ended March 31, 2015 and 2014 that were carried at the lower of amortized cost or fair value of the collateral less cost to sell. Accordingly, we recognized the existing credit loss reserves on these receivables as additional charge-off totaling $15 million and $20 million during the three months ended March 31, 2015 and 2014, respectively.

[3] These amounts represent TDR Loans for which we evaluate reserves using a discounted cash flow methodology. Each loan is individually identified as a TDR Loan and then grouped together with other TDR Loans with similar characteristics. The discounted cash flow impairment analysis is then applied to these groups of TDR Loans. The receivable balance above excludes TDR Loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell which totaled $399 million and $637 million at March 31, 2015 and 2014, respectively. The reserve component above excludes credit loss reserves for TDR Loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell which totaled $22 million and $39 million at March 31, 2015 and 2014, respectively. These receivables and credit loss reserves are reflected within receivables carried at the lower of amortized cost or fair value of the collateral less cost to sell in the table above.